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    Shaky ground Shaky ground Presentation Transcript

    • SHAKY GROUND 1. Label a cross-section of the earth which shows its four parts. 2. Describe the make-up of each layer. 3. Define the meaning of the terms crust, mantle, magma, inner core, outer core. 4. Recognise that the earth’s crust is broken up into pieces called tectonic plates. 5. Interpret a map of the world showing the tectonic plates and be able to name the two plates on which NZ lies. 6. Define the term continental drift and describe what causes this movement. 7. Describe the original super continent and it’s two parts. 8. Label a cross-section diagram of a volcano 4. Define weathering and describe how the major agents of physical (mechanical) and chemical weathering act. 5. Define erosion and describe how the major agents of erosion act. 6. Recognise the four types of volcanoes: shield, cone-shaped, dome and caldera. 7. Give the meaning of the terms: lava, vent, crater, ash, dormant, active, lahar. 13. Recognise the difference between continental and oceanic crust. 14. Explain how the process of subduction occurs, and how mid ocean ridges and trenches occur. 15. Explain what causes an earthquake. 16. Give the meaning of the terms: epicentre, focus, seismograph, s, and p waves, and Richter scale. 17. Recognise that most earthquake and volcanic activity is along plate boundaries. 18. Describe in simple terms, sedimentary, metamorphic and igneous rocks. Briefly describe the rock cycle. Sunday, 20 September 2009
    • LAYERS - labelling & describing Demo: The Scotch egg model of the earth’s structure Imagine a Scotch egg...... 1. (breadcrumbs) 2. (sausagemeat) 3. (egg white) 4. (egg yolk) Research - The earth’s structure http://www.windows.ucar.edu/tour/link=/earth/Interior_Structure/ interior.html Diameter = ________ km. The inner core is so ___ that it causes material in the outer core and ___________to move around. _____________ ____________ thin silicate rock material ___________ mostly solid (semi-liquid/plastic) and _________ consisting of ________ _________ liquid and consisting of ________ & _________ solid and consisting of ________ & _________ Sunday, 20 September 2009
    • HOW THICK ARE YOU?? Study the diagram carefully. It shows the earth’s layers. The depth in kilometres of the boundaries between layers is shown. 1. Put the thickness of the layers in order from thickest to thinnest. 2. A calculator may help. Thickest layer ____________ ____________ ____________ Thinnest layer ____________ Sunday, 20 September 2009
    • LAYERS - defining them Research - Definitions http://mediatheek.thinkquest.nl/~ll125/en/struct.htm Use the URL above to match the definition with the term with the composition with the thickness and with the average temperature Thickness Average Term Definition Composition (km) temp (oC) A. The layer above 1. Iron and Nickel. Extremely hot but (a) 2200 (i) 4500 Inner the core but below the pressure is low enough to allow it core the crust to exist as a liquid. B. The earth’s hard 2. Compounds of silicon, iron and (b) 15 (ii) 20 outer shell (which magnesium Outer floats on the softer to core part of the mantle) 870 C. The liquid layer 3. Rocks: Basalt and Granite (c) 1250 (iii) 3700 that surrounds and Mantle spins around the inner layer D. The solid, 4. Iron and Nickel. Extremely hot but (d) 2900 (iv) 2600 innermost part of under too much pressure to exist as a Crust the earth liquid. Sunday, 20 September 2009
    • UN-MIXING THE TABLE Answers Inner core ____ ____ ____ ____ Outer core ____ ____ ____ ____ Mantle ____ ____ ____ ____ Crust ____ ____ ____ _____ Now write the correct definitions for Inner core, Outer core, Mantle and Crust in the space provided (below): Definitions The inner core is ______________________________________________________ ____________________________________________________________________ The outer core is ______________________________________________________ ____________________________________________________________________ The mantle is ________________________________________________________ ____________________________________________________________________ The crust is __________________________________________________________ ____________________________________________________________________ Sunday, 20 September 2009
    • CONTINENTAL DRIFT The tectonic plates that make up the lithosphere float on the magma of the mantle. Hot magma near the outer core rises up towards the crust. When it gets there it cools enough to return to the core where it can be heated again and the cycle continues. This cycle results in circular currents called convection currents. Continental drift occurs when convection currents cause the tectonic plates to move. Practical MODELLING CONVECTION CURRENTS Method Tea leaves 1. Set up the equipment as shown. xxxxxxxxxxxxxxx 2. As you gently heat the beaker (using a blue flame) record your Bunsen observation of how the tea burner leaves move in the space below. Mat Observation ____________________________________________________________________ ____________________________________________________________________ ____________________________________________________________________ Sunday, 20 September 2009
    • TECTONIC PLATES A closer look at the crust: Lithosphere Stiffer part of the Athenosphere outer mantle and crust Liquid part of (floats on the the outer mantle athenosphere) The lithosphere is broken up into sections called tectonic plates. It is these plates that can float on the athenosphere Clickview video: Geography > “Global tectonics, Competing theories > Tectonic Plate Theory” Sunday, 20 September 2009
    • Oceanic Oceanic Sunday, 20 September 2009
    • CRUST MOVEMENT A ________________ boundary occurs where the lithospheric plates move away from each other Divergent boundaries form ____ - _________ ridges. The mid - Atlantic ridge is an example of a divergent plate boundary. A _________________ boundary occurs when the lithospheric plates move towards each other. Oceanic Oceanic If both plates are continental then the collision will result in ___________ formation. Continental Continental The Himalayan mountains are an example of a convergent boundary. When an oceanic plate moves towards a continental plate the heavier oceanic plate slides under the lighter continental plate. This is called a ____________ zone. A subduction zone is an area of intense activity. Continental _________, __________ eruptions and ___________ building all take place in a subduction zone. The Andes is a result of subduction Oceanic Words volcanic, mountain, divergent, convergent, mountain, subduction, mid, oceanic, earthquakes, Sunday, 20 September 2009
    • CRUSTS - continental and oceanic Oceanic crust Continental crust About 5 to 10 km thick about 30 to 70 km thick Consists mainly of heavy rocks like basalt Consists mainly of lighter rocks like granite Density: 3g per cubic centimetre Density: 2.8g per cubic centimetre Using the words “thinner, heavier, basalt and granite” describe the difference between the oceanic and continental crust. ____________________________________________________________________ ____________________________________________________________________ Sunday, 20 September 2009
    • RIDGES - a closer look Ridge Trench Ridge Continental Plate Oceanic Plate Oceanic Plate SPREADING SUBDUCTION Magma rises --> cools and expands when it contacts the ocean --> pushing of the oceanic plates apart --> Ridge formation as the magma piles up on the edge of each plate Study the diagrams carefully and use them to write a few sentences which explain how mid-ocean ridges and trenches are formed: Sunday, 20 September 2009
    • TECTONIC PLATES - mapped out The result of the cut & paste exercise New Zealand lies on two tectonic plates. Shade each plate carefully using a different colour Sunday, 20 September 2009
    • THE ORIGINAL SUPER CONTINENT Reading about it: http://kids.earth.nasa.gov/archive/pangaea/Pangaea_game.html 180 Million Years Ago About 180 million years ago the supercontinent Pangea began to break up. Scientists believe that Pangea broke apart for the same reason that the plates are moving today. The movement is caused by the convection currents that roll over in the upper zone of the mantle. This movement in the mantle causes the plates to move slowly across the surface of the Earth. About 200 million years ago Pangaea broke into two new continents Laurasia and Gondwanaland. Laurasia was made of the present day continents of North America (Greenland), Europe, and Asia. Gondwanaland was made of the present day continents of Antarctica, Australia, South America. The subcontinent of India was also part of Gondwanaland. Notice that at this time India was not connected to Asia. The huge ocean of Panthalassa remained but the Atlantic Ocean was going to be born soon with the splitting of North America from the Eurasian Plate. How do we know that South America was attached to Africa and not to North America 180 million years ago? Scientists today can read the history of the rock record by studying the age and mineral content of the rocks in a certain area. The Triple Junction was formed because of a three-way split in the crust allowing massive lava flows. The split was caused by an upwelling of magma that broke the crust in three directions and poured out lava over hundreds of square miles of Africa and South America. The rocks of the triple junction, which today is the west central portion of Africa and the east central portion of South America, are identical matches for age and mineral make up. In other words the rocks in these areas of the two continents were produced at the same time and in the same place. This tells us that South America and Africa were connected at one time! Today these two continents are separated by the Atlantic Ocean which is over 2000 miles wide! Sunday, 20 September 2009
    • 135 Million Years Ago About 135 million years ago Laurasia was still moving, and as it moved it broke up into the continents of North America, Europe and Asia (Eurasian plate). Gondwanaland also continued to spread apart and it broke up into the continents of Africa, Antarctica, Australia, South America, and the subcontinent of India. Arabia started to separate from Africa as the Red Sea opened up. The red arrows indicate the direction of the continental movements. Notice how far the Indian subcontinent has to move to get to its present position connected to Asia. The Atlantic, Indian, Arctic, and Pacific Oceans are all beginning to take shape as the continents move toward their present positions. The plates are still moving today making the Atlantic Ocean larger and the Pacific Ocean smaller. The yellow arrows on the world map indicate the direction of plates movements today. Notice the position of the Indian Subcontinent today. It moved hundreds of miles in 135 million years at a great speed (4 inches per year!!!) The Indian plate crashed into the Eurasian plate with such speed and force that it created the tallest mountain range on Earth, the Himalayas! What do you predict the world will look like in 100 million or 200 million years? What new mountain ranges will form? Where will new volcanoes erupt? The Atlantic Ocean will be much larger 50 million years from now and the Pacific Ocean will be much smaller. North and South America will have moved farther west (California moving north) while Greenland will be located farther west but also farther north. The western part of Africa will rotate clockwise and crash into Europe causing great mountain building, while the far eastern region of Africa will rotate eastward toward the Arabian peninsula. Australia will move farther north into the tropics, while New Zealand will move to the south of Australia. All of these predictions are just that, predictions. These movements of the continents may happen if the plates continue to move in the same direction and with the same speed as they are moving today. Scientists are not certain of the movement today, let alone 50 million years into the future. What do you think the world will look like in 50 million years??? Sunday, 20 September 2009
    • SUPER CONTINENTS 1. After reading “THE ORIGINAL SUPERCONTINENT”. cut and paste these pictures into your book in chronological order. 2. Label your pictures with how many years ago the situation existed 3. Answer the questions that follow. Sunday, 20 September 2009
    • Questions THE ORIGINAL SUPER CONTINENT 1. What is the name of the original super continent? 2. Why did this continent break up into smaller continents? 3. Describe the countries that are contained within Laurasia and Gondwanaland. 4. Explain how the triple junction was formed? 5. Describe the events that led to the formation of the triple junction. 6. What evidence do scientists have for the theory of continental drift illustrated by your pictures? Answers 1. Pangea 2. The movement was caused by convection currents that rolled over the upper zone of the mantle. 3. Laurasia consists of North America, Asia and Europe. Gondwanaland contains, South America, Africa, Arabia, Antartica, India and Australia. 4. The triple junction was caused by an upwelling of magma that caused a three way split in the crust. The crust split off in three different directions to form the continents South America, Africa/Arabia and Antarctica. The lava poured over large areas of Africa and America. 5. Scientists study the age and mineral content of rocks in the different continents and look for similarities (indicating that they could once have been part of the same land mass. Sunday, 20 September 2009
    • WORD LIST Magma reservoir Ash cloud Sill Vent Throat Summit Base Flank Lava Crater Conduit Dike Ash Parasitic cone Sunday, 20 September 2009
    • ANSWERS TO THE CUT & PASTE VOLCANO Sunday, 20 September 2009
    • Slideshow: Volcanoes Presentation VOLCANO TYPES Conc. H2SO4 + Sugar WHILE YOU WATCH THE SLIDE SHOW, LISTEN CAREFULLY and Match the volcano type with its description and the drawing of its shape 1. 1. SHIELD 2. COMPOSITE 3. RHYOLITE 4. CALDERA CONE OR DOME (ANDESITE) (i) Steep slopes (ii) Shallow (iii) forms a (iv) cone slopes lake shaped (a) (b) (c) (d) 2. Which volcano would be the most explosive? ___________________ 3. Explain the shape of the shield volcano? __________________________________ __________________________________________________________________ Sunday, 20 September 2009
    • Choose from the word list (right) to complete the sentences (below) Continental Oceanic plate plate (Heavier) (Lighter) Subduction zone 4. When an ___________ plate collides with a continental plate WORD LIST the ___________ plate goes under the ____________ plate. rocks This happens because the _______________ is ___________. extinct 5. As it goes under, the higher temperature of the mantle melts it volcano and the magma rises up through cracks as ________. This is lava how a _________ is formed. oceanic steam 6. Five things that pour out of a volcano during an eruption are active ___________ , ___________ , ____________ , ___________ dust and ______________ . continental dormant 7. An _________ volcano is one that is erupting. heavier 8. A sleeping volcano is called a ______________ volcano. It has crust not erupted for many years but may erupt at any time. ash 9. A dead volcano is called an _____________ volcano . Sunday, 20 September 2009
    • The Taupo volcanic zone includes volcanoes in the central North Island, Rotorua and the Bay of Reading about volcanoes Plenty. These volcanoes lie along the edge of the Pacific and Indo-Australian plates. Because the oceanic crust of the Pacific plate is sliding under the Indo-Australian plate, volcanic activity is seen on the continental crust of the Indo-Australian plate parallel to the plate boundary. There are different volcano types in the Taupo volcanic zone. This is because the different volcano types are created from magma from different depths along the subduction zone. The thickness of magma (how easily it flows) depends on its depth and temperature. Basalt volcanoes are formed from the eruption of thin, runny magma which comes from deep along the subduction zone where the temperature is high. This magma also has a low silica content. Taupo Volcanic Zone Sunday, 20 September 2009
    • Silica thickens the magma and since the silica content is low the magma that forms basalt volcanoes is thin and runny. The magma that escapes from the crust to form a Basalt volcano is basic (the opposite to being acidic) and the eruptions that form the slopes of the volcano are mild. At the other extreme, if the magma comes from a shallow region of the subduction zone, where the temperature is much lower, Rhyolite volcanoes are formed. This magma which is at a lower temperature also has a high silica content and is therefore thicker and reluctant to flow easily. The magma is acidic. This results in steep sided volcanoes like Mount Tauhara and Mount Maunganui. These mountains were formed by violent eruptions. Lake Taupo was originally a rhyolite dome volcano. Pressure under the mountain rapidly dropped after a violent explosion which caused the crust to collapse. This formed a caldera. The explosion was so violent that the ash turned the sky red over Rome and China. The crater that remained filled with water to form a large lake. Andesite volcanoes are formed from magma which has a thickness, silica content and acidity which is somewhere between the basic magma of basalt volcanoes and the acidic magma of rhyolite volcanoes. Sunday, 20 September 2009
    • VOLCANO TYPES Once you have completed the reading, complete the summary table below: 2.COMPOSITE 3.RHYOLITE 1.SHIELD CONE OR 4.CALDERA DOME (ANDESITE) Sketch (showing the shape) Eruption type Thickness of the magma Silica content A NZ example Sunday, 20 September 2009
    • A SUMMARY Lava is ___________and Lava is ___________and slow-cooling so it cools ________so it is spreads out more before not able to spread out as it solidifies far before it solidifies Pressure drops in the mantle so the lithosphere collapses Lava is ___________and cools __________ so it is not able to spread out as far before it solidifies Sunday, 20 September 2009
    • What has caused these changes? Sunday, 20 September 2009
    • What has caused these changes? WAVE ACTION Sunday, 20 September 2009
    • What has caused these changes? WAVE ACTION STREAM ACTION Sunday, 20 September 2009
    • What has caused these changes? WAVE ACTION STREAM ACTION WAVE ACTION Sunday, 20 September 2009
    • What has caused these changes? EARTH MARS Sunday, 20 September 2009
    • What has caused these changes? EARTH MARS BOTH CAUSED BY WIND Sunday, 20 September 2009
    • What has caused these changes? Sunday, 20 September 2009
    • What has caused these changes? ICE AND ROCKS, FALLING UNDER THE INFLUENCE OF GRAVITY Sunday, 20 September 2009
    • What has caused these changes? Sunday, 20 September 2009
    • What has caused these changes? ALTERNATING HEATING AND COOLING Sunday, 20 September 2009
    • What has caused these changes? Sunday, 20 September 2009
    • What has caused these changes? PLANT ROOTS GROWING INTO THE ROCK Sunday, 20 September 2009
    • What has caused these changes? Sunday, 20 September 2009
    • What has caused these changes? ACID RAIN Sunday, 20 September 2009
    • What has caused these changes? When marble contains sulphide minerals and undergoes oxidation, the Iron II will produce rust spots, and the sulfur is converted to sulphuric acid, which can dissolve calcium. During oxidation Iron II is converted to Iron III. Sunday, 20 September 2009
    • What has caused these changes? CHEMICAL WEATHERING (CALLED OXIDATION) When marble contains sulphide minerals and undergoes oxidation, the Iron II will produce rust spots, and the sulfur is converted to sulphuric acid, which can dissolve calcium. During oxidation Iron II is converted to Iron III. Sunday, 20 September 2009
    • Frost Wedging (or Freeze - Thaw) There often needs to be a repetitive cycle of freezing and thawing (melting) Glaciers Weathering takes place in glaciers but not by the action of frost because the water is not freezing and thawing so regularly. Instead _____________________________________ _____________________________________ _____________________________________ This is the Fox Glacier in New Zealand. The sheet of ice is constantly moving down the mountain side, breaking off rock as it goes and carrying those pieces down the valley. Sunday, 20 September 2009
    • WEATHERING SUMMARY Weathering is the process by which rocks are broken down. Weathering can be Mechanical or chemical. Mechanical weathering • Water can dissolve soluble rock or wear away insoluble rock through the action of waves, streams or rainfall. • Wind blows pieces of sand over rocks, wearing away softer rock • Ice and rocks falling under the influence of gravity can wear away the sides of mountains forming valleys. • Alternating heating and cooling can break down rocks over time because the rock contains different materials that expand differently. This forces the materials apart and causes the rock to be broken down into smaller pieces. • Frost action can break up rocks because when water freezes in cracks it expands, forcing the rock to split. • Plant roots can grow in rocks and as they do so they can break the rock up into smaller pieces. Chemical Weathering • Acid rain reacts with the calcium in rocks causing them to break down. • Oxidation occurs when the iron sulphide minerals in marble react with oxygen to form rust. Sunday, 20 September 2009
    • EROSION AND ITS AGENTS Erosion is the transportation of rock, soil, and mineral particles. It is this transportation that causes material to be worn away. Erosion and weathering often occur together Sources of erosion: Gravity Water (running water, glaciers, and rain) Wind Waves EXAMPLES ________________ ________________ Sunday, 20 September 2009
    • EROSION AND ITS AGENTS Erosion is the transportation of rock, soil, and mineral particles. It is this transportation that causes material to be worn away. Erosion and weathering often occur together Sources of erosion: Gravity Water (running water, glaciers, and rain) Wind Waves EXAMPLES ________________ ________________ Sunday, 20 September 2009
    • Type of weathering (Mechanical/Chemical/Biological) A B C D E 1.Copy this table into F the back of your G H book. I 2.Complete it as you J K view the slides L which follow M N O P Sunday, 20 September 2009
    • A Sunday, 20 September 2009
    • B Sunday, 20 September 2009
    • C Sunday, 20 September 2009
    • D Sunday, 20 September 2009
    • E Sunday, 20 September 2009
    • F Sunday, 20 September 2009
    • G Sunday, 20 September 2009
    • H Sunday, 20 September 2009
    • I Sunday, 20 September 2009
    • J Sunday, 20 September 2009
    • K Sunday, 20 September 2009
    • L Sunday, 20 September 2009
    • M Sunday, 20 September 2009
    • N Sunday, 20 September 2009
    • O Sunday, 20 September 2009
    • P Sunday, 20 September 2009
    • Type of weathering - Answers A Mechanical (wind) B Mechanical (water) C Mechanical (Freeze - thaw) D Chemical weathering (acid rain) E Mechanical (Alternate heating & cooling) F Mechanical (Gravity causing Glaciers to scour out valley) G Chemical (acid rain) H Mechanical (Gravity causing Glaciers to scour out valley) I Biological weathering J Mechanical (Alternate heating & cooling) K Mechanical (Wave action) L Chemical weathering M Biological weathering N Chemical weathering (acid rain) O Biological weathering P Biological weathering Sunday, 20 September 2009
    • Study the pictures (below) and for each picture state the source/s of erosion responsible for the observed changes. Explain how the changes occurred Farmland _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ Desert rocks _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ Mountain slopes _______________________________________________________ _______________________________________________________ _______________________________________________________ _______________________________________________________ Stream _______________________________________________________ Sunday, 20 September 2009
    • EARTHQUAKES - causes An earthquake is a vibration of the earth caused by a rapid release of energy. Earthquakes are commonly caused by subduction where there is friction (between the oceanic and the continental plate) which is suddenly released. New Zealand has many earthquakes because it is situated over subduction zones. These are often called faults but aren’t. A fault is where the plates crash into each other without either plate sliding under the other. Faults can also cause earthquakes. 1. Either read p112 & 113 (Pathfinder 10) or research earthquakes on the internet. 2. Complete the following definitions Epicentre ___________________________________________________________ Focus ___________________________________________________________ Seismograph ________________________________________________________ s waves ________________________________________________________ p waves ________________________________________________________ Richter scale _________________________________________________________ • The Taupo-Rotorua “fault” causes the Bay of Plenty Earthquakes. • There are 2 types of earthquake waves: P and S. • A seismometer can pick up these waves. This produces a seismogram: P waves arrive first, S waves arrive later. The time difference tells us how far away the quake is Mini assignment - “Reading the traces” from Wignall and Wales (Y10 Homework Book) Sunday, 20 September 2009
    • THE ALPINE FAULT - forming the Southern Alps Sunday, 20 September 2009
    • READING ABOUT IT Over the past 25 million years, the land either side of the alpine fault moved vertically creating the Southern alps (which are about 4 km high) The amount of uplift that has occurred is much greater than 4km (some estimates put it at 20 km) The height has been kept down due to weathering and erosion In South Island two continental crusts, the Indo-Australian and the Pacific plate crash into each other. Of course, where the plates meet, rocks crash (very slowly) together with tremendous power. Folding (bending) and faulting (fracturing, breaking) of rocks occur. Faulting and folding lead to mountain building . The southern alps Mountain building occurs Continental Continental Mantle Sunday, 20 September 2009
    • PUTTING EARTHQUAKES ON THE MAP Cut & Paste Most earthquakes in New Zealand occur along the main ranges living from Fiordland in the southeast to East Cape in the northwest. This axis follows the boundary between the Indo- Australian and Pacific plates. Large earthquakes are less common along the central Alpine Fault, where the plates are not subducting and the forces are accommodated in different ways. The largest city within this high risk zone is the nation's capital, Wellington, followed by Napier and Hastings. All these cities have nch experienced severe earthquakes since ng i tre European settlement. ura Hik After reading the above paragraphs, put the locations (in bold print, on the map) Sunday, 20 September 2009
    • ROCK TYPES AND THE ROCK CYCLE http://www.windows.ucar.edu/tour/link=/earth/geology/rocks_intro.html When a volcano erupts, the magma reaches the surface as lava. Lava cools to form rocks called igneous rocks. Igneous rocks contain crystals which are the result of the cooling process. When lava cools quickly, the crystals are small (as they are in basalt). Osidian is an exception. It cools rapidly but without crystal growth. Air can also be trapped in the lava as it cools rapidly (to form rocks like pumice or scoria). Slow cooling results in larger crystals to produce rocks like granite. Over time igneous rocks are eroded and the particles (sediments) collect in rivers and oceans. This material is buried and compacted to form sedimentary rocks (such as sandstone and mudstone). Sedimentary rocks can be recognised from the existence of particles such as sand, mud and pebbles. Sedimentary rocks allow scientists to learn about the environment that existed when the layers were formed. Fossils are evidence of living things trapped in the sediments before they became rocks. Scientists can also learn about climate change from these layers. Sedimentary rock that finds itself in deeper, hotter regions of the crust can change into metamorphic rocks. Metamorphic rocks are formed from sedimentary rocks that have been subjected to heat and pressure. This occurs in places where tectonic plates are coming together. When metamorphic rocks melt they become part of the magma. This leaves volcanoes as lava which cools to form igneous rocks and the cycle continues. Sunday, 20 September 2009
    • SORTING OUT THE ROCK CYCLE Cut & paste the picture (below) into your book. Choose from the labels (right) to complete the flow chart. • Melting • Deposition of sediment • Burial & compaction • Erosion & transport • Weathering of rocks at surface • Crystallisation of magma • Deformation & metamorphism Sunday, 20 September 2009
    • SORTING OUT THE ROCK CYCLE Cut & paste the picture (below) into your book. Choose from the labels (right) to complete the flow chart. • Melting • Deposition of sediment • Burial & compaction • Erosion & transport • Weathering of rocks at surface • Crystallisation of magma • Deformation & metamorphism Sunday, 20 September 2009
    • A For this rock and the rocks on the next few slides, try to figure out what type of rock it is Sunday, 20 September 2009
    • B Sunday, 20 September 2009
    • C Schist Sunday, 20 September 2009
    • D Granite Sunday, 20 September 2009
    • E Sunday, 20 September 2009
    • F Sunday, 20 September 2009
    • G Sunday, 20 September 2009
    • H Sunday, 20 September 2009
    • I Obsidian Sunday, 20 September 2009
    • J Sunday, 20 September 2009
    • K Sunday, 20 September 2009
    • L Sunday, 20 September 2009
    • M Sunday, 20 September 2009
    • ROCK TYPE - answers A Metamorphic B Igneous C Metamorphic D Igneous E Sedimentary F Sedimentary G Metamorphic H Metamorphic I Igneous J Sedimentary K Igneous L Metamorphic M Sedimentary Sunday, 20 September 2009
    • Red rock canyon, las Vegas. The gray mountains are limestone and the red and white hills are sandstone. Blocks of marble, a metamorphic rock, are cut from a quarry in Carrara, Italy. Metamorphic rock, Kaikoura. Sunday, 20 September 2009
    • the San Andreas Fault zone which exhibits 1500km of movement in about 10 million years, as the North American Plate has slid to the northwest relative to the Pacific Plate. Sunday, 20 September 2009
    • Revision questions WEATHERING & EROSION Over time ___________ smooths mountains and reduces their height. __________ weathering breaks down rock into smaller pieces whereas chemical ________ breaks rocks down into simpler substances. Mechanical weathering can occur in a range of ways: • ________ carries sand that scours rocks • ________ washes rocks down rivers where they break up • ________ in cracks in rocks which freezes, expands and split rocks • ________ roots grow in cracks, grow and split rocks Chemical weathering also has a range of causes • Oxygen reacts with ________ in the rock, breaking them down • _________ slowly dissolves rocks • _________ in rain dissolves rock especially carbonate After rocks have been broken down by weathering. Rocks move from the mountains towards the sea in a process called _________. Moving air (i.e. ______) can carry small particles. Massive ice fields (____________) move rocks along with them. Most erosion however is carried out by ____________ Word List wind water water erosion chemical mechanical glaciers acid transportation metals plant wind water water Sunday, 20 September 2009
    • Answers WEATHERING & EROSION Over time ___________ smooths mountains and reduces their height. __________ weathering breaks down rock into smaller pieces whereas chemical ________ breaks rocks down into simpler substances. Mechanical weathering can occur in a range of ways: • ________ carries sand that scours rocks • ________ washes rocks down rivers where they break up • ________ in cracks in rocks which freezes, expands and split rocks • ________ roots grow in cracks, grow and split rocks Chemical weathering also has a range of causes • Oxygen reacts with ________ in the rock, breaking them down • _________ slowly dissolves rocks • _________ in rain dissolves rock especially carbonate After rocks have been broken down by weathering. Rocks move from the mountains towards the sea in a process called _________. Moving air (i.e. ______) can carry small particles. Massive ice fields (____________) move rocks along with them. Most erosion however is carried out by ____________ Answers - listed left to right erosion mechanical chemical wind water water plant metals water acid transportation wind glaciers water Sunday, 20 September 2009
    • HOW WE LEARNT ABOUT THE EARTH’S LAYERS If it were possible to drill a hole to the center of the Earth, about 2,900 km below the surface the drill bit would reach the Earth's core. First the drill would bore through the solid, relatively low density rock of the crust. Then anywhere from 7 to 50 km below the surface the bit would encounter the much denser rock of Earth's mantle. Finally it would reach the core, which consists of an outer molten layer beginning at about 2,900 km and then an inner solid crystalline mass starting at about 5,100 km. Sometimes called the centrosphere, or the Earth's innermost layer, the core was almost a complete mystery until the development of the science of seismology and seismic instruments. Seismographs reveal the nature of the vibrations, or seismic waves, produced during an earthquake. As seismologists learned more about seismic waves, they realized they could use them to interpret the density and structure of the Earth's interior. In 1897, a discovery by the Irish scientist Richard Dixon Oldham provided early clues about the nature of Earth's interior. He found that (seismic) waves generated by explosions or earthquakes travel through the interior of the Earth in different directions and at different speeds. The two basic types of seismic waves discovered by Oldham are known as body waves--those that move through the Earth's interior, and surface waves - those that travel only along the surface. There are two kinds of body waves: primary and secondary waves. Primary or P waves, cause compressional movement emanating from the source of the disturbance. Secondary or S waves, produce shear motion in a direction perpendicular to the P wave. While P waves can pass through gases, liquids, and solids, S waves can only penetrate through solid matter. Seismic waves have also helped scientists learn the various densities of the Earth's many layers because the speed of primary shock waves moving through the Earth generally increases with depth. This is because as density increases, seismic wave velocity increases. While P-waves travel through the Earth's crust at an average of about 6.4 km per second, they reach an average of 11.3 km per second at the center of the Earth. When the shock waves suddenly shift in direction and speed, scientists are able to determine the depths at which Earth's various layers are located. Sunday, 20 September 2009
    • HOW WE LEARNT ABOUT THE EARTH’S LAYERS If it were possible to drill a hole to the center of the Earth, about 2,900 km below the surface the drill bit would reach the Earth's core. First the drill would bore through the solid, relatively low density rock of the crust. Then anywhere from 7 to 50 km below the surface the bit would encounter the much denser rock of Earth's mantle. Finally it would reach the core, which consists of an outer molten layer beginning at about 2,900 km and then an inner solid crystalline mass starting at about 5,100 km. Sometimes called the centrosphere, or the Earth's innermost layer, the core was almost a complete mystery until the development of the science of seismology and seismic instruments. Seismographs reveal the nature of the vibrations, or seismic waves, produced during an earthquake. As seismologists learned more about seismic waves, they realized they could use them to interpret the density and structure of the Earth's interior. In 1897, a discovery by the Irish scientist Richard Dixon Oldham provided early clues about the nature of Earth's interior. He found that (seismic) waves generated by explosions or earthquakes travel through the interior of the Earth in different directions and at different speeds. The two basic types of seismic waves discovered by Oldham are known as body waves--those that move through the Earth's interior, and surface waves - those that travel only along the surface. There are two kinds of body waves: primary and secondary waves. Primary or P waves, cause compressional movement emanating from the source of the disturbance. Secondary or S waves, produce shear motion in a direction perpendicular to the P wave. While P waves can pass through gases, liquids, and solids, S waves can only penetrate through solid matter. Seismic waves have also helped scientists learn the various densities of the Earth's many layers because the speed of primary shock waves moving through the Earth generally increases with depth. This is because as density increases, seismic wave velocity increases. While P-waves travel through the Earth's crust at an average of about 6.4 km per second, they reach an average of 11.3 km per second at the center of the Earth. When the shock waves suddenly shift in direction and speed, scientists are able to determine the depths at which Earth's various layers are located. Sunday, 20 September 2009
    • In 1906, Oldham recognized the existence of the Earth's core and made a preliminary, but incorrect, estimate of its size. He also noted a seismic "shadow zone," on the side of the Earth opposite the earthquake, where no P waves were recorded. Although uncertain, he presumed this resulted from refraction, or bending of waves, similar to light passing through a glass lens. In 1926, British seismologist Harold Jeffreys recognized an S wave shadow zone that begins 103 degrees from an earthquake and forms a "bullseye" shaped shadow on the backside of the Earth where no S waves are recorded. This indicated that the core was molten, since shear waves cannot pass through liquids. Oldham's work, which included partially successful attempts to determine the existence of a thin outer crust and an inner core, helped other scientists accurately map the Earth's different layers. In 1909, Andrija Mohorovicic (1857-1936) published important findings from his study of an earthquake that hit Croatia. Based on his analysis of P and S wave speeds and arrival times, he was able to calculate the depth of the boundary where material changes from the Earth's crust to its mantle. This important discovery resulted in his name being applied to that boundary, called the Mohorovicic discontinuity, or the Moho for short. In 1914, based on seismic wave studies, Beno Gutenberg estimated the diameter of the core to be about 4,375 mi (7,000 km), a figure that still stands today. In tribute to that discovery, the boundary where the mantle and the core meet is referred to as the Gutenberg Discontinuity. In 1936, Danish seismologist Inge Lehmann hypothesized the existence of an inner core within the Earth's deepest interior, based on receipt of weak P waves in the P shadow zone and presented her arguments using elementary trigonometry. She believed that by passing through the boundary from an outer core to an inner core, P waves could be refracted and received within the P wave shadow zone. For the next two years, Gutenberg and Charles F. Richter (1900-1985) worked on the problem and helped confirm Lehmann's hypothesis that the core had both an inner and an outer shell. The size of the inner core, however, and whether it was solid, liquid, or a mixture of both could not be established at that time. Further studies during the 1940s by K.E. Bullen showed that the inner core was solid, while the outer core was liquid. This change in phase probably results from the immense pressures at this depth. Sunday, 20 September 2009
    • Unlike the rock of Earth's mantle and crust, the core is thought to be composed almost entirely of metal, largely iron in the outer core, with an alloy of iron and nickel in the inner core. It is, of course, impossible to sample the core directly. What are believed to be minute inclusions of mantle material are sometimes found in diamonds, as well as from other sources; however, no such fragments of the Earth's core have ever been found, nor are they ever likely to be. Instead, geologists have had to find another source for study. Planetary geologists believe that Earth formed from material very similar to that of meteorites. Stony meteorites are considered to be representative of the mantle, while iron meteorites are representative of the core. Therefore, geologists base their estimates of the composition of the Earth's core on studies of meteorites. In 1996 researchers Xiaodong Song and Paul Richards of the Lamont-Dougherty Earth Observatory discovered that the inner core rotates freely within the low viscosity fluid of the outer core. The finding confirmed what seismologists had suspected for years: the highly fluid iron of the outer core allowed the inner core to move independently of the rest of the Earth. They discovered this by noting that on seismic records for earthquakes from different years, P waves following the same path through the inner core had different travel times. These waves must be traveling along different paths through the inner core, a result of its rotation. In addition, they determined that the inner core rotates about one-quarter turn faster than the crust and mantle each century, or about one degree faster per year. Computer models suggest this is due to two jet stream-like currents flowing through the outer core. These carry a magnetic field that "tugs" on the inner core and gives its rate of rotation an extra "boost." Later that same year other researchers confirmed their findings. Answer the following questions in the BACK OF YOUR BOOK 1. Describe how early knowledge of the earth’s structure was gained. 2. Name the two types of waves that scientists studied in order to learn about the earth’s structure. 3. How did scientists discover that the inner outer core was molten? 4. Where did scientists get clues from about the composition of the core? Sunday, 20 September 2009
    • KEY WORDS 4 THE TOPIC Word Search mantle crust D Z G G S N C F W U E Z C Q E crater epicentre A O D N B A O K E C R A T E R core weathering E R R Q T C I I A T Y K J S O dormant L A E M C N O I T C U D B U S focus erosion T C C D A O E R H C B V Y C I volcano N C Y T L N N V E O E V C O O active seismograph A E B C I A T T R T O V V F N shield M R E I Z V C G I K S O N Z K cone lahar C T U E B U E Y N N L U L O D Richter H N L A H A R F G C E Q R O C dome caldera S E I S M O G R A P H N M C T tectonic C C T E C T O N I C H E T O V lava vent O I A V A L O D L E I H S A P subduction N P S P R E T H C I R W I P L convection continental E E E V U I W K I A D U V B P Sunday, 20 September 2009
    • MAKING A GLOSSARY 1 WORD Ans Definition 1. Mantle A. powdery material thrown out of a volcano 2. Crust B. describes a cone-shaped volcano 3. Core C. Outer, thin layer of the earth consisting of rocky material 4. Lava D. hole in the earth’s crust where an eruption may occur 5. Vent E. has not erupted for a long time but can erupt 6. Crater F. describes a volcano which has erupted violently to form a huge hollow which can fill with water to become a lake 7. Ash G. describes a volcano which has shallow slopes 8. Lahar H. a mountain which has a vent through which material from the mantle can be ejected 9. Dormant I. magma that has cooled above the surface 10. Active J. describes a volcano that has steep slopes 11. Volcano K. mud flow 12. Shield L. thick layer of semi-liquid rock 13. Cone M. central part of the earth, inner core is solid, outer is liquid 14. Dome N. currently erupting 15. Caldera O. a large cavity forming the mouth of a volcano Sunday, 20 September 2009
    • MAKING A GLOSSARY 2 WORD Ans Definition 1. Lithosphere A. describes the crust underlying the continents B. point on the earth’s surface above the focus of an 2. Asthenosphere earthquake 3. Subduction C. breaking down of rocks on the earth’s surface 4. Convection D. transport of rock fragments and other material 5. Continental E. upper mantle below lithosphere made of plastic rock 6. Oceanic F. Sinking of one tectonic plate edge below another 7. Erosion G. point where an earthquake starts 8. Weathering H. describes currents formed by the rising of hot, less dense material 9. Richter I. describes crust underlying the oceans 10. Epicentre J. upper mantle consisting of rigid rock 11. Focus K. instruments which record earthquake waves 12. Seismograph L. plates of lithosphere underlying continents & oceans 13. Tectonic M. scale for measuring the size of an earthquake Sunday, 20 September 2009
    • THE BIG SHAKY GROUND CROSSWORD Sunday, 20 September 2009
    • THE BIG SHAKY GROUND CROSSWORD Sunday, 20 September 2009
    • PUZZLE OVER THIS Sunday, 20 September 2009
    • PUZZLE OVER THIS Sunday, 20 September 2009
    • REVISION CROSSWORD Sunday, 20 September 2009
    • REVISION CROSSWORD Sunday, 20 September 2009